Richard Cowen wrote:
The fact that bats and pterosaurs don't use a supracoracoideus system in their flight doesn't mean that birds can do without it.
No, it doesn't.However, the supracoracoideus has been surgically
disconnected in modern birds (pigeons, I believe), and they continue to
fly just fine after the surgery. That experiment probably indicates that
birds can fly without it since those surgically altered birds did so.
The reasons they could are fairly obvious. Removing it just means that
the birds will avoid flying in some slower speed ranges.